Use existing phone number without the ability to read a QR-code (Landline)

[Buchheister]

I have a very specific problem and maybe someone can help with it. I'm using latest HAOS on a Raspberry.

For quite a while, I'm using Signal with Home Assistant with success. The phone number registered is a landline.
Now I'm setting up a second instance of Home Assistant in another location. Somehow I can't figure out how to register the the new instance of Home Assistant as a secondary device at the same landline number.

Following the instructions in the manual, I can get a QR-code image. Since the number is a landline I have no way to scan it like suggested.

Is there a way to register a second device with Signal on Home Assistant with the first one being a landline number?

Thanks a lot in advance and keep up the great work. It is highly appreciated.
Georg